This is just plain weird.
I\'ve got Rails 3 RC running with Devise installed. I\'ve defined a custom strategy to try and use Kerberos for authentication.
I have run into a similar problem. After a short session of debugging I found out the reason. My user was not confirmed, so after initial successful signing in with my strategy, he was logged out by one of the following modules which is confirmable module :)
Btw, the easiest way to debug rails application is to use following code:
require 'ruby-debug'
Debugger.wait_connection = true
Debugger.start_remote
debugger
and then rdebug -c from terminal.